Elevated interest and participation in sport after an Olympic Games are frequently associated with activity-related injuries associated with the increase in demands on our musculoskeletal system. The accumulation of minor repetitive damage to bone is the process by which stress-related bone injury occurs and can lead to stress fractures of the metatarsal foot bones as Mr Michael Oddy, ISEH Consultant Trauma & Orthopaedic Surgeon reports:
"Microscopic damage to bone is normally constantly repaired by the cellular process of remodelling whereby bone is removed by osteoclast cell resorption and then re-laid by osteoblast cells. When the rate of damage accumulation exceeds the ability to repair, there is a resulting loss of the normal bone architecture. Like any engineering structure or material, this can result in fatigue failure, which is the process by which bone stress injuries develop and lead to stress fractures. Normal bone homeostasis, the biological process of maintaining a stable state, also requires the correct balance of hormones, calcium and vitamin D, the subtle deficiency of which is surprisingly common in the population and a risk for bone failure.
The development of a stress fracture in the foot is most commonly related to a change or increase in activity. The classic metatarsal march fracture in a new army recruit is the result of the increased intensity of basic military route march training often carrying a load. The same process and presentation can occur with increased treadmill use or road-running training. Diagnosis of a stress-related injury can be frustrating for those engaged in sports and medical professionals alike. The absence of definite trauma with bruising means the date of onset of symptoms can be vague and there is frequently a period when continued sports participation is possible, with pain gradually developing earlier in training as the bone stress increases until an actual fracture occurs.
Clinical assessment of the foot can highlight certain mechanical problems which can predispose to a stress fracture. A tight Achilles' tendon prevents the supple upward dorsiflexion of the foot at the ankle and this increases the time and force loading the front foot during walking and running. A bunion or hallux valgus deformity de-functions the load-bearing ability of the big toe forcing more body weight onto the adjacent more slender lesser metatarsals. This effect can be compounded by a foot with a big toe first metatarsal shorter than the lesser second metatarsal, the eponymously named Morton's foot which can be chronically associated with load transfer hard skin under the central forefoot reflecting the mechanical increase in pressure.
An initial plain X-ray may be normal in appearance if performed within the first few weeks unless a complete fracture in the cortical edge of the bone is visible. The characteristic history suggesting a stress fracture should warrant a further X-ray a few weeks later which may show the dramatic development of early new bone callus around the injury. Absence of callus by six weeks after the onset of pain, in the absence of any other clear findings, should prompt more sensitive imaging with a Magnetic Resonance Imaging (MRI) scan which can demonstrate the spectrum of bone stress oedema to a definite fracture in great detail. An MRI might also elucidate other causes of forefoot metatarsalgia pain which can become symptomatic with running such as joint inflammation capsulitis, inter-metatarsal bursitis or an enlarged inter-metatarsal nerve or neuroma.
Initial treatment of a metatarsal bone stress injury is cessation of impact loading such as running. Many can continue to walk in normal shoes or cushioned training shoes but significant pain should be offloaded with a short pneumatic walker boot for anywhere up to six weeks until a good callus reaction on X-ray demonstrates evidence for progression of healing. Diffuse bone bruising with oedema of a bone stress injury without fracture can be harder to manage as there may be no sign of new bone callus formation and being very sensitive, the changes on MRI take many months to resolve. Impact loading such as running training is not advisable for four to six weeks after resolution of foot pain. Initial return to aerobic fitness may need supervision of a physiotherapist or sports trainer where indicated, with cross-training methods and non-impact aqua jogging being ideal forms of rehabilitation from injury.
The Olympic cycle is a four year programme and A Year on Foot at the ISEH wants to remind the armchair enthusiast that the best way to avoid the stress of sustaining an injury or fracture is with the paced introduction of a new sporting activity."